Electric switch



March 31. 1925v 1,531,917

H. G. FRENCH ELECTRIC SWITCH Filed Nov. ll, 19122l Figi.

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Patented Mar. 31, 1925.

UNITED STATES PATENT oFFlcE.

HENRYG. FRENCH, F SCHENECTADY, NEW YORK, ASSIGrNOR T0 GENERAL ELECTRICCOMPANY,

A. CORPORATION 0F NEW YORK.

ELECTRIC SxWITCH..

Application led November 11, 1922.A Serial No. 600,202.

l To all 'whom t may concern.

Be it known that I, HENRY Gr. FRENCH,

a citizen of the United States, residing at Schenectady, in the countyof Schenectady, State of New York, have invented certain -new and usefulImprovements in Electric Switches, of which the following is a speci-Iication.

My invention relates to electric'switches and more particularly todisconnecting or contact devices of the relatively movable cooperatingtype and has for an object to provide an improved contact device of suchflexibility and construction as to insure that l5 the relatively movablecontacts register correctly for a highly efficient electric contactirrespective of niceties in alignment of the parts supporting thecontacts. Another object of my invention is to provide an improvedflexible contact which, irrespective of its alignment with thecooperating con-- tact, is upon disengagement therefrom alu wayspositively self-restoring or self-aligning to substantially the sameposition.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing and its scope will bepointed out in`-the appended claims.'

Figure 1` is an elevation partly in section, illustrating an embodimentof my invention, the supporting members of the relatively movable'contacts -being shown in alignment; Fig. 2 is an elevation similar tol? ig. 1 but showing the contact supporting members out of alignment,and Fig. 3 illustrates an application of the embodiment of my inventionshown in Figs. 1 and 2 to a switch structure of the removable truckpanel type shown in elevation with parts broken away for clearness.

In switch gear embodying relativelyT movable cooperating contacts, it isfrequently difficult and often impractical to employ the refinements ofconstruction and adjustments necessary to a precise alignment of thecon- `tact supporting structures so as to insure that the contacts willregister with that nicety essential to a highly efficient electriccont-act. Even though the refinements of construction and adjustmentsare carried to an extreme, the complex structure of modern switchgear,the inevitable Wear of the parts,

shocks and jars of operation which disturb the adjustments, and othercauses make it very troublesome and diiiicult particularly in contactdevices of the plug and socket ty e to obtain an efficient electriccontact, principally because of variations and inaccuracies in thealignment of the contact supporting structures. According to myinvention, I provide an improved construction of contacts which obviatesthis difficulty and renders unnecessary the refinements of constructionrequisite -to a precise alignment of the contact supporting structuresand therefore provides a more economical and efficient construction.which is capable of withstanding relatively hard use.

In the figures of the accompanying drawing, I have illustrated anembodiment of my invention in an electric switching or disconnectingdevice of the plug and socket type comprising relatively movablecooperating contacts, one of which may be fixed. The fixed contactmember is shown as the socket part of the switching device and maycomprise a terminal or contact such as a tube 1 which for the purpose ofmounting preferably has integral therewith a. mounting member such as astud 'or bolt 2 also serving as a conducting member. The tube 1 isprovided With a flaring or mouth portion 3 in order better to receiveand guide the engaging parts of the cooperating contact. The mouth 3 maybe frusto-conical in shape and may be integral with the tube 1 or asshown may comprise a separate piece forced over a reduced section 4 ofthe tube 1, the end of the tube being then spun over a portion of theinner surface of the mouth to provide a smooth passageway and also tosecure the mouth to the tube.

My invention particularly resides in the contact device whichconstitutes thefplug part of the electric switching or disconnectingdevice and is herein shown as the coopaxis of the plug.

preferably two of erating movable contact. The contact device comprisesa terminal 5 which is provided with a substantially hollow cylindricalportion 6 and also suitable mounting means such as a stud or bolt 7which may be an integral part of the'terminal. 'A conducting contactmember, such as a plug 8, preferably provided with an enlargedsubstantially spheroidal end 9, a portion of the surface of whichadjacent the shank or body of the plug 8 may be substantially flat orconcave thus forming a substantially well defined line of demarcation orintersection of the spherical and flat or concave surfaces to provide arelatively sharp fulcruming edge 10 for a purpose hereinafter to be setforth. The points forming this line or edge are preferably coplanar anddefine a plane which is preferably perpendicular to the The fulcrumingedge l0 is thus adjacent the body of the plug 8- and is substantially acircle concentric with the plug. The enlarged end 9 of the plug 8 isthus substantially in the shape of a segment of a sphere, the diameterof which is preferably somewhat larger than the 'diameter of thecylindrical portion 6 of the terminal 5. In order that the enlarged endportion 9 may enter the cylinder 6 and be capable of movement thereinfor a yielding joint and an efficient electric contact, the end oftheplug 8 is provided with one or more slots such as saw cuts 11, therebeing these slots which` may be made substantially perpendicular to eachother. Inthis way, there is provided a substantialresilient connectionaffording a good electric contact. In accordance with my invention, I sosecure the plug 8 to the terminal 5 as to, provide a sliding ball andsocket or universal joint, that is to say one in which there is no fixedpivotal connectiony between the cooperating parts of the joint. For thispurpose the cyllnder or socket 6 may be counterbored or recessed to seata suitable bearing `member such as a split washer 12 which is set inplace after inserting the spherical portion or ball 9 into the socket 6.The socket 6 may then be spun over the washer 12 to retain the same andtherefore to maintain the assembly. For contact engagement with the tube1, the free end ofthe plug 8 may also be provided with a convex curvedportion 13 which as shown is substantially in the shape of a prolatespheroid `whose smallest diameter is somewhat greater than the innerdiameter of the tube 1, this end of the plug also being provided withslots 14 which may be saw cuts to provide a substantial resilientconnection, affording a good electric contact'. The shape of the ball 13also provides for readily guiding this end of t-he plug 8 through themouth 3 into the tube ll. In order to provide a flexible mounting forthe plug 8 so that it may readily be eflected upon entering the mouth 8and so that it may be self-restoring or aligning to a given positionwhen withdrawn from the tube 1, I provide suitable resilient means suchas a helical spring 15, one end of which as shown may embrace orsurround the cylinder 6 and a bearing the other end of which may engagea holding member such as a flanged collar 16 restrained in place at anintermediate point on the plug 8 by a pin 17. The collar 16 ispreferably insulating material so that the Spring 15 does not carrycurrent thereby eliminating any possible deleterious effects upon thestatic properties of the spring material from heating. rIhe spring 15 asshown is arranged to be restrained under compression so as to exert aforce tending to spread the lug 8 and the terminal 5 apart but allowingboth linear and angular movement of the terminal 5.

Referring now to Fig. 2 in which the supports of the tubular contact 1and the terminal 5 are shown out of alignment, it will be evident that,as the plug 8 is moved toward the contact 1, the enlarged end 13 willengage the flaring mouth 8 and be guided thereby into' the tubularContact 1. The plug 8 will therefore be deflected out of alignment withthe terminal 5 and the fulcruming edge 10 will not be in bearingthroughout its length on the washer 12 as shown in Fig. 1, but willinstead be in bearing on the one point, the lowest point as shown inFig. 2. rlhe spring 15 is also deflected, the coils on the upper sidebeing somewhat compressed and on the lower side somewhat distended. Thisflexure of the spring 12 of course tends to return the plug 8 intoalignment with the terminal 5 when the contacts are .disengaged but theforce resulting from this flexure of the spring 12 is very frequentlyinsuflicient to align the plug 8, since there must of necessity beconsiderable friction between the enlarged end 9 and the cylindricalportion 6 of the terminal 5 to insure an eicient electric contact.Consequently, the vplug 8 might upon disengagement of the contacts beheld by this friction in spite of the flexure of the spring 15 so farout of alignment as to register incorrectl with the mouth 3 when it isagain desiree to make contact. By my invention, however, it will beobvious that when the plug 8 is eanted or moved out of alignment withthe terminal 5, there results a positively self-restoring orself-aligning moment or torque whose force is the resultant stress inthe spring 15 which is in compression in the illustrated embodiment ofmy invention, exerted in a direction substantially coincident with theaxis of the plug 8 and whose lever arm is the perpenplug 8 relatively tothe lOl.

washer at substantially only pivot al center,

- truck 19. In

dicular distance from the point Where the fulcruming edge 10 bears onthe Washer 12 to the axis of the plug 8. This self-aligning torque isrelatively constant since the lever arm is the radius of thecircumferential fulcruming edge 10 and the movable pivotal center of theplug 8, that is to say the center of the enlarged end 9 is free to shiftor move to the left as shown in Fig. 2 substantially in line with theaxis of the terminal 5. Because of this shifting to the left of the thespring 15 is shortened, resulting in more compression in the spring. Theresultant spring force therefore tends to increase somewhat inproportion to the increase in angular displacement of the plug 8 which.is of course desirable since this makes the restoring torque increasewith increased displacement of the plug 8. There is, therefore, at alltimes when the plug 8 is not in alignment with the terminal 5, apositive self-aligning moment, clockwise with reference to the'showingin Fig. 2, tending to turn the plug 8 into alignment with the terminal5, that is, to a position Where the fulcruming edge 10 comes to an evenbearing on the Washer 12 as shown in Fig. 1 and the self-aligning momentbecomes substantially the same in every direction, since the axis of theplug is in alignment with the terminal and the tendency for the spring15 to turn-'the plug 8 is the same in every direction as the resultantforce exerted by the spring is substantially in alignment with the axisof the plug 8 and the terminals 5 and merely tends to separate or spreadthem apart in this direction.

In Fig. 3 I have illustrated one application of the embodiment of myinvention shown in Figs. 1 and 2 as a disconnecting device used inconnection with the secondary circuits of switchgear known to the art asthe removable truck panel type. This switchgear comprises a housing orcubicle 18 and a truck 19 arranged to be moved into and out of thehousing 18. Mounted in the housing 18 at the rear thereof aredistributing bus bars 2() and incoming leads 21, the particulararrangement shown being for a three phase alternating current system.The truck 19 has mounted thereon a suitable circuit breaker 22 arrangedto be controlled by an operating mechanism 23 to complete a circuit fromthe bus bars 2O through primary disconnecting devices 24 and leads 25 tothe incoming leads 21. Suitable auxiliary devices for operating relays,measuring and indicating instruments, etc. which maybe mounted on thetruck panel, such as current arid potential transformers 26 and 27 arealso mounted on the installations embodying this type of switchgear, itis often necessary and desirable to run secondary circuits for meters,relays, etc., from one panel to another but as the meters, relays, etc.,are usually mounted on the trucks, they are movable relatively to thecontrol circuits to which they are to be connected andI my disconnectingdevice is particularly applicable to this use. These secondary circuitsmay for example, as illustrated in Fig. 3, comprisecontrol buses 28carried in suitable insulating supports 28 Within a conduit or-housing29 supported on top of the truck panel housings 18. Also supported bythe housing 1S on the interior thereof in any suitable manner andinsulated therefrom is a tubular contact 1 comprising a mouth -1 asillustrated in Figs. 1 and 2, that is to say the socket part of mydisconnecting device which may be connected to one of the buses 28 by aconductor 30. Mounted on the truck 19 and insulated therefrom is thecooperating orA plug part of my disconnecting device as embodied inFigs. 1 and 2, the tei'- minal 5 thereof being connected by a conductor31 -to an electrical device 32, such as a meter, relay, etc. mounted onthe panel 33 of the truck 19. There may, of course, be more than one ofthese disconnecting devices but as they are usually mounted side byside, only one shows in the elevation as in Fig. 3. 1n the applicationof my invention shown, the tubular contact 1 is preferably made thetixed and live contact because of its extreme simplicity of constructionand therefore slight'probability of getting out of order. lVhile themovable VContact comprising the plug 8 is of more complex structure, itis dead when the truck 19 is removed and is therefore convenientlyaccessible for inspection and repairs.-

Vith switchgear structure of the type illustrated in Fig. 3, it will 'beobvious that if the disconnecting or contact devices are of suchconstruction as to necessitate a precise alignment of the contactsupporting structures, an inordinatel amount of time and labor isnecessary to accomplish the requisite refinements of adjustment.Moreover as the truck panels are generally made interchangeable and asit is frequently desirable to provide spares, slight variations in the.adjustments of the mountings increase the difficulty. Also dirt or otherforeign matter either on or under the truck 'Wheels results inmisalignment of the supporting structures. Furthermore, the switchgearis subject to a certain amount of more or less hard use in operation andthis tends to disturb any refinements in adjustment. By the use ofcontact devices embodying my invention, however, the necessity of suchnicet-y of adjustment of the contact supporting structures is eliminatedas the flexible construction of thecontact device comprising the plug 8permits considerable leeway in all directions with respect to thealignment of the contact supporting contact.

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structures. This reduces cost and simplifies operation and insures thatthe cooperating contacts will register with that nicety requisite to aneiiicient electric Contact.

While I have shown and described only one embodiment of my invention, Ido not desire to be limited to the exact arrangement shown and describedbut seek to cover in the appended claims all those modiications thatfall within the true spirit and scope of my invention.

I'Vhat I claim as new and desire to secure by Letters Patent of theUnited States, is

l. In an electric contact tact member provided at one cruming edgesubstantially concentric with the axis of said member, a terminalarranged to retain the fulcruming edged end of said member and providedwith a bearing for said fulcruming edge, and resilient means constructedand arranged to exert a force tending to turn said contact member aboutthe fulcruming edge thereof on said bearing into alignment with saidterminal.

2. In an electriccontact device, a contact member provided at one endwith a fulcruming edge substantially concentric with the axis of saidmember, a terminal comprising a ho'llow member within which thet'ulcruming edged end ot said contact member is mounted, means forretaining the tulcruming edged end of said contact member in said hollowmember arranged to provide a bearing for the fulcruming edge of saidcontact member, and resilient means constructed and arranged to exert aforce tending to turn said contact member about the fulcruming edgethereof on said retaining means into alignment with said terminal.

3. In an electric Contact device, a contact member provided at one endwith a fulcruming edge substantially concentric with the axis of saidmember. a terminal comprising a hollow member within which thefulcruming edged end of said contact member is mounted, means forretaining the fulcruming edged end of said contact member in said hollowmember arranged to provide a beardevice, a conend with a fuling for thefulcruming edge of said contact member. and a helical compression springsurrounding said terminal and said contact member and exerting a forcetending to turn said contact member about the fulcruming edge thereof onsaid retaining means into alignment with said terminal.

4. In an electric contact device, a contact member having an enlargedend provided with a fulcruniing edge substantially concentric with theaxis ot the member. a terminal con'lprising a hollow substantiallycylindrical member within which the enlarged end of said contact memberis slidably mounted. means for retaining the enlarged end of saidcontact member in said cylindrical member arranged to provide a bearingfor said fulcruming edge, an insulating collar mounted on said contactmember, and means tending to turn said contact member about saidfulcruming edge on said retaining means into alignment With saidterminal comprising a helical spring arranged concentrically with theaxis of said Contact member and having one end surroundingsaidcylindrical member and the other end engaging said insulating collarwhereby said spring is insulated from said contact member.

5. In an electric contact device, a contact member having an enlargedsubstantially spheroidal end provided with a fulcruming edge, a terminalcomprising a hollow substantially cylindrical member having the enlargedend of said contact member slidably mounted therein and cooperatingtherewith to form a sliding ball and socket joint. means ltor retainingthe end of said contact member within said cylindrical member arrangedto provide a bearing for the fulcruming edge of said end, and resilientmeans constructed and arranged to exert a force tending to turn saidContact member about said fulcruming edge on said retaining means intoalignment with said terminal.

6. In an electric Contact device, a contact member having an enlargedsubstantially spheroidal end provided with a relatively sharpcircumferential edge adjacent the body of the member and substantiallyconcentric therewith, a terminal havin;r a hollow substantiallycylindrical portion with the enlarged end of said contact memberslidably mounted therein and cooperating therewith to form a slidingball and socket joint, means associated with said terminal for retainingthe enlarged end of the contact member in the cylindrical portion of theterminal arranged to provide a bearing surface on which said contactmember is movable abo-ut the edge of the enlarged end thereof, andresilient means adapted to allow movement of said contact memberrelatively to said terminal and arranged to exerta force tending to turnsaid contact member about said edge on said retaining means intoalignment with the terminal.

7. In an electric contact device. a contact member having an enlargedsubstantially spheroidal end provided with a relatively sharpcircumferential edge adjacent the body of lthe member and substantiallyconcentric therewith, a terminal having a hollow substantiallycylindrical portion with the enlarged end of said contact memberslidablv mounted therein and cooperating therewith to form a slidingball and socket joint, retaining means associated with said terminalconstructed and arranged to provide a bearing surface on which saidcontact member is movable about the edge of the enlarged end thereof andcomprising a Harige on the oyabout said edge o n the bearing surface oflindrioal portion of said terminal i''on-retain-v said retaining meansinto alignment with the ing said enlarged end therein, and resilientterminal.

means associated With said Contact member In 'Witness whereof, I havehereunto set 'Y 5 and Said terminal adapted to allow relamyhandthis 9thday of November, 1922.

tive movement thereof and arranged to exert i a force tending to turnsaid Contact member HENRY G. FRENCH.

